Dewatering device and pressure feeder



Feb. 20, 1962 M. E. GINAVEN 3,021,78

DEWATERING DEVICE AND PRESSURE FEEDER Filed March 27, 1959 2 Sheets-Sheet 1 Candi INVENTOR NfliW/V 6'. 67/107 Va /V iim m Feb. 20, 1962 M. E. GlNAVEN DEWATERING DEVICE AND PRESSURE FEEDER 2 Sheets-Sheet 2 Filed March 27, 1959 ilite tats 3,021,782 DEWATERENG DEVlCE AND PRESSURE FEEDER Mmvin E. Ginaven, Springfield, Ohio, assignor to The Ban: Bros. (30., Springfield, Ghio, a corporation of Ohio Filed Mar. 27, 1959, Ser. No. 802,508 8 Claims. (Cl. 100-146) This invention relates to pulp processing equipment, and particularly to a generally new device in the working and treatment of pulp useful to a quick and efiicient removal of fluids for a predetermined thickening of the pulp.

The object of the invention is to simplify the construction as well as the means and mode of operation of dewatering devices, whereby such devices may not only utilizing screw presses, with the view of obviating delivery to the screw press of heavily watered pulp which cannot effectively be thickened by action in the screw press alone.

A further object of the invention is to introduce a dewatering device especially characterized by means positively propelling pulp stock in a continuous feed through system and in the course thereof applying changing pressures bringing about a release of water from the stock.

Still another object of the invention is to introduce a principle of counter rotating feed screws in a dewate'ring device as described cooperating to eliminate the need for breaker bars, resistors and other devices to prevent the pulp material from a smooth passage along the flights of the feed screw.

A further object of the invention is to provide a dewatering device possessing the advantageous structural features, the inherent meritorious characteristics and the mode of operation herein mentioned.

With the above and other incidental objects in View as will more fully appear in the specification, the invention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations thereof, and the mode of operation as hereinafter described or illustrated in the accompanying drawings, or their equivalents.

Referring to the accompanying drawing wherein is shown one but obviously not necessarily the only form of embodiment of the invention,

slotted cage for the feed screw mechanism; and

.the order of sixty-five percent.

3fi2lfi82 Patented Feb. 20, 1%62 FIG. 5 is a detail view taken substantially along the line 5-5 of FIG. 4.

Like parts are indicated by similar characters of refer ence throughout the several views.

The invention may have different applications in the pulp process art. For example, in the working of pulp it frequently becomes necessary to change the consistency of the suspension. Screening and cleaning of the pulp usually is carried out with the pulp at a very low percentage of solids, as for example on the order of one half of one percent. After cleaning and screening the next step in the pulp treatment process is one of refining. To do this eifectively, the pulp consistency must be increased to somewhere between four and eight percent solids. Also, when pulp is placed in storage it is desirable to increase the consistency to the maximum consistency which can be pumped, which is about six percent. A pre-press or dewatering device in accordance with the instant invention would be arranged in a processing system to receive screened and cleaned pulp, thicken it to a consistency on the order of six percent and then direct it to the refiners or to a storage chest in accordance with the requirements of the work. In another application, the device of the instant invention serves as a pre-press in the sense that it is stationed in the system in advance of a screw press for further extraction of liquid. Acting as a pre-press, the device accepts a watered pulp at a relatively low consistency, as on the order of four percent, and thickens it to a. substantially higher consistency, as on the order of fifteen to sixteen percent. The thickened pulp accordingly may then be directly discharged into the screw press which will extract the remaining water and bring the final pulp up to a relatively high percentage of solids as on it will be understood that if the watered pulp at four percent were delivered directly to the screw press the ability of the screw press to defiber the pulp and to produce a dried pulp material would be adversely affected since the press is not equipped to remove and carry off large amounts of water. Thus, the water which can he removed with cornparatively little effort is taken off in the pro-press, leaving for the screw press the task of expressing water which is more difficult of removal.

Referring to the drawings, a dewatering device in accordance with the illustrated embodiment of the invention takes the form of a unitary machine forming a part of a continuous pulp treatment process, and being stationed to receive watered pulp material under pressure and to deliver the dewatered or thickened pulp stock selectively to storage or to another processing stage such'as to a screw press or to refiners. Referring to the drawings, a generally cylindrical base casting lil arises from a fioor plate 11. A transverse wall 12 in the 'base iii defines a case 13 receiving the lower ends of electric motor 24 outside the base 10 andin adjacent relation thereto. The motor. 24 efiects a powered rotation of a shaft 25 on which is a sprocket 26 in common engagement, along with sprocket wheel 21, with the chain 22. Rotation of the sprocket 26 accordingly is accompanied by a corresponding rotation of sprocket wheel 21. and of the shaft 15 to which it is secured. The gear 19 turns with the shaft 15 and through its meshing gear 18 effects a corresponding turning motion of the shaft 14. The shafts 14 and 15 rotate counter to one another or in opposite directions.

Above the transverse wall 12 in the base it) a vertically rising wall 27 defines a central generally oval shaped chamber 28, and, exteriorly thereof, a generally annular area 29. A fitting 31 on one side of the base casting 19 provides an entrance Way to a cored passage 32 in the base casting which extends transversely through the annular space 29 and communicates through an opening 33 with the chamber 28. Passage 32 constitutes the pulp inlet, a watered pulp being pumped to such inlet and thence into the chamber 28. The space 29 communicates with the exterior of the base casting through an opening 34 terminating in a fitting 35. Outlet 34, as will hereinafter more clearly appear, serves as an outlet for water released from the pulp in its passage through the machine. At the upper end of the base casting 10, the space 29 is bridged at diametrically opposed points by mounting blocks 36 and 37 which provide mounts for vertical uprights '56 and 39. The latter have respective lateral flanges or feet 41 and 42 bolted to the parts 36 and 37. Further comprised in the structure of the vertical uprights are angle portions 43 and 44 which assist in supporting a jacket in surrounding relation to the feed screws, such jacket being made up of mating, half cylindrical portions 45 and 46 clamped together at their adjoining ends as by bolts 47. Interposed between the angular portions 43 and 44 of the upright structures and the respective joints between the jacket sections 45 and 46 are rubber or rubber-like sealing gaskets 48 and 49 which tend to make such joints water tight. At the upper ends of the upright structure is mounted a closing plate 51. The upper ends of'the jacket sections 45 and 46 abut the periphery of the plate 51 and maintain a sealed engagement therewith through a ring seal 52 recessed in the periphery of the plate. A similar contact is made by the lower ends of the jacket sections with a sealing ring 53 mounted on the upper end of the base casting 10.

The jacket 4546 defines a space 54 closed at its top by the plate 51 and open at its bottom to drain freely into the chamber 29 in the base 16 communicating with outlet 34. Extending upwardly in the space 54, in effeet as an extension of the oval shaped wall 27 in the base, is a cage made up of complementary cage section assemblies 55 and 56. At its upper and lower ends cage section 55 is received in and suitably secured to, as by welding, curved plate segments 57 and 58 which are respectively mounted to the upper closure plate and lower bridge parts 36 and 37 and which at their ends abut the uprights 38 and 39. Similar curved segments 59 and 61 provide a mounting for opposite ends of cage section 56. The cage sections are identical so that a description of one will sufiice for both. Thus, and referring to FIGS. 4 and 5, each cage section is essentially comprised of a plurality of longitudinally extending elongated wires or small size rods 62 arranged in a laterally curving formation and spaced from one another. Transversely extending, longitudinally spaced apart, bars 63 are wrapped around the exterior of the plurality of rods 62 and are individually welded to the rods to define and to maintain a predetermined spaced relation of the rods, as well as maintaining a unitary relation between the rods and laterally extending bars. The ends of the bars 63terminate' in and are welded to longitudinally extending marginalpieces 64 and 65 which are in turn bolted to the uprights 33 and 39.

The cage sections 55 and 6'6 are diametrically opposed on opposite sides of the uprights 38 and 39 and cooperate therewith in defining an enclosure for the feed sc ews 16 and 17, which enclosure may be considered a pressure and feed passage 66, being in effect an upward continuation of chamber 28 in the base 10. The passage 66 has, moreover, limited communication with the space 5 outwardly thereof through the slots between bars 62. These slots run parallel to the axes of the feed screws 16 and 17, and as indicated in FIG. 5, have an outwardly flaring configuration due to a triangular crosssectional shape given to the rods 62. The rods 62 are arranged with their apices facing outward or into the space 54. As a result, at the inner periphery of the cage section the slots have a minimum width which gradually is increased in a radial direction. The arrangement is one providing for a free flow of fluids out of the passage 66. The movement of solids through the slots of the cage largely is prevented and such solids as are able to escape through the relatively narrow slots at the inner periphery of the cage are given an expanded space in which to leave the outer periphery of the cage thereby avoiding clogging. The arrangement of the cage sections 55 and 56 further is such to place their inner peripheries into conforming relation to flights on the feed screws; Being thus in effect wiped by the peripheries of the feed screws, the inner surfaces of the cages 55 and 56 are continuously cleaned of clinging solids so that in terior'clogging also is avoided. The triangular formation of the rods 62 in effect provide sharp edged openings and no opportunity is provided for solids to become lodged in such openings. I

The feed screws respectively comprise shafts 66 and 67 having integrally wound thereon helicoid surfaces 68 and 69. The surfaces 68 and 69 constitute the flights of the screws and have a constant pitch as well as opposite directions of inclination. Thus, the surface 68 has what may be termed a left hand spiral while the surface 69 of screw 17 has a right hand spiral. Since the direction of rotation of the screws is counter to one another both thus rotate in a directiontoraise imcoming pulp material from the chamber 28 upwardly through the passage 66. The feed screws are in parallel adjacent relation with the helicoid surfaces 68 and 69 thereof overlapping at their peripheries, or, in effect, interfitting, The shafts 66 and 67 of the feed screws are connected at their lower ends to the aforementioned stub shafts 14 and 15. Rotation of the shafts 14 and 15 accordingly efiects a corresponding rotation of the feed screws. In response thereto pulp material admitted to the chamber 28 is lifted therefrom on the helicoid surfaces 68 and 69 and elevated in continuous feed manner to the top of the device. The upper ends of the feed screws pass through an opening 71 in the upper closure plate 51. At their upper extremities the feed screws are connected to stub shafts 72 and 73 having a rotary mounting in a bearing housing 74. The latter is connected to and forms a part of a duct section 74 acting as the discharge outlet for dewatered pulp stock, being adapted to be connected in a suitable discharge line. The duct 74- is connected to and aligned with a housing 75 seated on the closure plate 51 in a superposed position with respect to opening 71 therein. The duct or housing 75 has sloping sides to provide an interior of lesser cross-sectional area than the chamber or passage 66'. The upper ends of the feed screws project into the housing 75 and the terminals of the helicoid flights 68 and 69 arereduced in width to be accommodated within the smaller cross-sectional area of the housing. The reduced discharge area, it will be understood, operates to impose a back pressure upon or a resistance to movement of the pulp material out of the passage 66. There is, accordingly, a tendency to build up pressure within the passage 66, the elf ect of whichis to express fluids from the moving pulp material. The released fluids leave the passage'66' through the slots in cage sections 55 and 56 and enter space 54 where they are free to descend into the base chamber 2 and leave the device by way of outlet 34. In the meantime, the solids continue to rise in response to rotation of the feed screws and are moved through the housing 75 into duct 74 and then conducted to storage or a further processing stage.

The construction and arrangement of the feed screws 16 and 17, with their interfitting surfaces 68 and 69, is such as to move the pulp material upwardly in essentially a straight line without appreciable rotary movement with either of the screws. Thus, in the interests of obtaining a squeezing action upon the pulp material as it passes through the feed screw mechanism it is desirable to avoid a smooth rotary passage of the material from one end of a screw to the other. It has been known heretofore to obviate this motion in a screw press and the like by interposing breaker bars or resistors and the like which act to minimize the rotary motion or" the material. According to the instant inventive concept, however, rotary movement of the pulp is avoided through the use of twin interfitting screws which because of their counter rotation define an interference zone intermediate the axes of the screws where the overlapping helicoid surfaces interpose themselves in the path of movement of the pulp material over the companion surface and interrupt such movement, transferring portions of the pulp from one surface to another. The result is that the bulk of the pulp material moves vertically and approximately in a straight line through the feed screw assembly without appreciable rotary motion. Also, the overlapping of the helicoid surfaces in effect reduces the space between adjacent flights of the feed screw means in the interference zone. As a result, increased pressures occur in this zone, further effective in obtaining an expression of fluids from the pulp material. A positive means of propelling the pulp stock through the drainage cage accordingly is provided which is effective also to subject the pulp to changing pressures for a high rate of release of fluids from the pulp.

The device of the invention has been shown in an upright position as it is used standing erect on a floor. It can be used in other positions, as for example, positioned on its side with the outlet duct 74 communicating directly with the inlet of a screw press. In this instance the liquid outlet is rearranged so as to provide for gravity drainage of the expressed fluid away from the drainage cage.

The spacing in the drainage cage, between the rods 62, as well as the rod size, is selected for use with specific pulp materials or groups of materials to achieve a maximum passage of fluids with a maximum restriction of solid matter. The drain cage provides a large open area, which is self-cleaning in response to movement of the helicoid surfaces 625 and 69 thereover. The changing pressures inside the passage 65' cause a rapid expression of fluids from the pulp fibers as they are moved from the cage surface in a thickened felt-like formation and compacted in the zone of higher pressure where the interfitting screw flights pass each other.

From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated as desirable, but which obviously is susceptible of modification in its form, pro-portions, detail construction and arrangement of parts without departing from the principle involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise but one of several modes of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

Having thus described my invention, I claim:

1. In the art of pulp processing, a pulp thickening device including a pair of feed screws in parallel nearby relation to one another, means supporting said screws for rotation, said screws including shafts of uniform diameter and continuous lefthand and righthand helicoid surfaces on said respective shafts inter-fitting with one another to define spaced apart low clearance zones intermediate said screws, a closely fitting cage having an inlet and an outlet, said cage surrounding said screws to contain the pulp solids in their movement along said feed screws from said inlet to said outlet while permitting escape of released fluids therefrom, a restrictive extension on said cage at said outlet exercising a restrictive influence upon movement of the pulp therethrough, said screws extending into said restrictive extension, means introducing a fluid pulp into said inlet at one end of said screws, and means for rotating said screws in opposite directions, the helicoid surfaces thereof conducting the pulp toward said outlet conditions of intermittently applied and released pressure.

2. A pulp thickening device according to claim 1, characterized in that said cage includes a substantially smooth interior surface wiped clean by the edges of said helicoid surfaces as they move relative said cage.

3. A pulp thickening device according to claim 1, characterized in that said cage includes at least in part a plurality of parallel bars having an approximately triangular shape in cross-section and extending in parallel relation with the axes of said feed screws.

4. A pulp thickening device according to claim 1, characterized in that said cage includes at least in part a series of spaced apart parallel bars, the axes of which are parallel with the axes of said feed screws, and slots defined intermediate said spaced apart parallel bars through which fluids expressed from the pulp are discharged.

5. A device according to claim 1 characterized in that said spaced apart low clearance zones intermediate said screws inhibit rotation of the pulp solids in unison with rotation of the screws.

6. A device according to claim 1 characterized in that the axes of said feed screws and said housing are in vertically extending parallel relation.

7. In the art of material processing, a material thickening device including a pair of feed screws in parallel nearby relation to one another, means supporting said screws for rotation, said screws including shafts of uniform diameter and continuous lefthand and righthand helicoid surfaces on said respective shafts interfitting with one another, a perforated housing having an inlet and an outlet surrounding and enclosing said feed screws to contain the material in its movement along said feed screws from said inlet to said outlet while permitting escape of released fluids through the perforations therein, a housing extension of restricted area at said outlet exercising a restriction upon movement of the material therethrough, said screws extending into said restricted extension, means introducing a fluid suspension of material into said inlet, and means for rotating said screws in opposite directions, the helicoid surfaces conducting the material longitudinally of the housing from the inlet to the outlet, overlapping edges of the interfitting helicoid surfaces defining interference zones inhibiting rotation of the material with either screw and establishing intermittent relatively high pressure areas for fluid expression.

8. A pressure feeder and dew-atering device for processing material suspensions, including a pair of feed screws in parallel nearby relation to one another, means supporting said screws for rotation, said screws including shafts of uniform diameter and continuous lefthand and righthand helicoid surfaces on said respective shafts interfitting with one another, a cage enclosing said feed screws having an inlet and an outlet to contain the material in its movement along said feed screws from said inlet to said outlet while permitting escape of released fluids therethrough, an extension of restricted area at said outlet exercising a restriction upon movement of the material therethrough, said screws extending into said restricted extension, means introducing a fluid suspension of material into said inlet, and means for rotating said screws in opposite directions, the helicoid surfaces conducting the materal longitudinally of the housing from the inlet to the outlet, overlapping edges of the interfitting helicoid surfaces defining spaced apart low clearance zones therebetween for intermittent application and release of pressure on said material for extraction of fluid therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 

